rocksdb/table/cuckoo_table_reader.cc
sdong 35ad531be3 Seperate InternalIterator from Iterator
Summary:
Separate a new class InternalIterator from class Iterator, when the look-up is done internally, which also means they operate on key with sequence ID and type.

This change will enable potential future optimizations but for now InternalIterator's functions are still the same as Iterator's.
At the same time, separate the cleanup function to a separate class and let both of InternalIterator and Iterator inherit from it.

Test Plan: Run all existing tests.

Reviewers: igor, yhchiang, anthony, kradhakrishnan, IslamAbdelRahman, rven

Reviewed By: rven

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D48549
2015-10-13 15:32:13 -07:00

379 lines
13 KiB
C++

// Copyright (c) 2014, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef ROCKSDB_LITE
#include "table/cuckoo_table_reader.h"
#include <algorithm>
#include <limits>
#include <string>
#include <utility>
#include <vector>
#include "rocksdb/iterator.h"
#include "rocksdb/table.h"
#include "table/internal_iterator.h"
#include "table/meta_blocks.h"
#include "table/cuckoo_table_factory.h"
#include "table/get_context.h"
#include "util/arena.h"
#include "util/coding.h"
namespace rocksdb {
namespace {
const uint64_t CACHE_LINE_MASK = ~((uint64_t)CACHE_LINE_SIZE - 1);
const uint32_t kInvalidIndex = std::numeric_limits<uint32_t>::max();
}
extern const uint64_t kCuckooTableMagicNumber;
CuckooTableReader::CuckooTableReader(
const ImmutableCFOptions& ioptions,
std::unique_ptr<RandomAccessFileReader>&& file, uint64_t file_size,
const Comparator* comparator,
uint64_t (*get_slice_hash)(const Slice&, uint32_t, uint64_t))
: file_(std::move(file)),
ucomp_(comparator),
get_slice_hash_(get_slice_hash) {
if (!ioptions.allow_mmap_reads) {
status_ = Status::InvalidArgument("File is not mmaped");
}
TableProperties* props = nullptr;
status_ = ReadTableProperties(file_.get(), file_size, kCuckooTableMagicNumber,
ioptions.env, ioptions.info_log, &props);
if (!status_.ok()) {
return;
}
table_props_.reset(props);
auto& user_props = props->user_collected_properties;
auto hash_funs = user_props.find(CuckooTablePropertyNames::kNumHashFunc);
if (hash_funs == user_props.end()) {
status_ = Status::Corruption("Number of hash functions not found");
return;
}
num_hash_func_ = *reinterpret_cast<const uint32_t*>(hash_funs->second.data());
auto unused_key = user_props.find(CuckooTablePropertyNames::kEmptyKey);
if (unused_key == user_props.end()) {
status_ = Status::Corruption("Empty bucket value not found");
return;
}
unused_key_ = unused_key->second;
key_length_ = static_cast<uint32_t>(props->fixed_key_len);
auto user_key_len = user_props.find(CuckooTablePropertyNames::kUserKeyLength);
if (user_key_len == user_props.end()) {
status_ = Status::Corruption("User key length not found");
return;
}
user_key_length_ = *reinterpret_cast<const uint32_t*>(
user_key_len->second.data());
auto value_length = user_props.find(CuckooTablePropertyNames::kValueLength);
if (value_length == user_props.end()) {
status_ = Status::Corruption("Value length not found");
return;
}
value_length_ = *reinterpret_cast<const uint32_t*>(
value_length->second.data());
bucket_length_ = key_length_ + value_length_;
auto hash_table_size = user_props.find(
CuckooTablePropertyNames::kHashTableSize);
if (hash_table_size == user_props.end()) {
status_ = Status::Corruption("Hash table size not found");
return;
}
table_size_ = *reinterpret_cast<const uint64_t*>(
hash_table_size->second.data());
auto is_last_level = user_props.find(CuckooTablePropertyNames::kIsLastLevel);
if (is_last_level == user_props.end()) {
status_ = Status::Corruption("Is last level not found");
return;
}
is_last_level_ = *reinterpret_cast<const bool*>(is_last_level->second.data());
auto identity_as_first_hash = user_props.find(
CuckooTablePropertyNames::kIdentityAsFirstHash);
if (identity_as_first_hash == user_props.end()) {
status_ = Status::Corruption("identity as first hash not found");
return;
}
identity_as_first_hash_ = *reinterpret_cast<const bool*>(
identity_as_first_hash->second.data());
auto use_module_hash = user_props.find(
CuckooTablePropertyNames::kUseModuleHash);
if (use_module_hash == user_props.end()) {
status_ = Status::Corruption("hash type is not found");
return;
}
use_module_hash_ = *reinterpret_cast<const bool*>(
use_module_hash->second.data());
auto cuckoo_block_size = user_props.find(
CuckooTablePropertyNames::kCuckooBlockSize);
if (cuckoo_block_size == user_props.end()) {
status_ = Status::Corruption("Cuckoo block size not found");
return;
}
cuckoo_block_size_ = *reinterpret_cast<const uint32_t*>(
cuckoo_block_size->second.data());
cuckoo_block_bytes_minus_one_ = cuckoo_block_size_ * bucket_length_ - 1;
status_ = file_->Read(0, file_size, &file_data_, nullptr);
}
Status CuckooTableReader::Get(const ReadOptions& readOptions, const Slice& key,
GetContext* get_context) {
assert(key.size() == key_length_ + (is_last_level_ ? 8 : 0));
Slice user_key = ExtractUserKey(key);
for (uint32_t hash_cnt = 0; hash_cnt < num_hash_func_; ++hash_cnt) {
uint64_t offset = bucket_length_ * CuckooHash(
user_key, hash_cnt, use_module_hash_, table_size_,
identity_as_first_hash_, get_slice_hash_);
const char* bucket = &file_data_.data()[offset];
for (uint32_t block_idx = 0; block_idx < cuckoo_block_size_;
++block_idx, bucket += bucket_length_) {
if (ucomp_->Equal(Slice(unused_key_.data(), user_key.size()),
Slice(bucket, user_key.size()))) {
return Status::OK();
}
// Here, we compare only the user key part as we support only one entry
// per user key and we don't support sanpshot.
if (ucomp_->Equal(user_key, Slice(bucket, user_key.size()))) {
Slice value(bucket + key_length_, value_length_);
if (is_last_level_) {
get_context->SaveValue(value);
} else {
Slice full_key(bucket, key_length_);
ParsedInternalKey found_ikey;
ParseInternalKey(full_key, &found_ikey);
get_context->SaveValue(found_ikey, value);
}
// We don't support merge operations. So, we return here.
return Status::OK();
}
}
}
return Status::OK();
}
void CuckooTableReader::Prepare(const Slice& key) {
// Prefetch the first Cuckoo Block.
Slice user_key = ExtractUserKey(key);
uint64_t addr = reinterpret_cast<uint64_t>(file_data_.data()) +
bucket_length_ * CuckooHash(user_key, 0, use_module_hash_, table_size_,
identity_as_first_hash_, nullptr);
uint64_t end_addr = addr + cuckoo_block_bytes_minus_one_;
for (addr &= CACHE_LINE_MASK; addr < end_addr; addr += CACHE_LINE_SIZE) {
PREFETCH(reinterpret_cast<const char*>(addr), 0, 3);
}
}
class CuckooTableIterator : public InternalIterator {
public:
explicit CuckooTableIterator(CuckooTableReader* reader);
~CuckooTableIterator() {}
bool Valid() const override;
void SeekToFirst() override;
void SeekToLast() override;
void Seek(const Slice& target) override;
void Next() override;
void Prev() override;
Slice key() const override;
Slice value() const override;
Status status() const override { return status_; }
void InitIfNeeded();
private:
struct BucketComparator {
BucketComparator(const Slice& file_data, const Comparator* ucomp,
uint32_t bucket_len, uint32_t user_key_len,
const Slice& target = Slice())
: file_data_(file_data),
ucomp_(ucomp),
bucket_len_(bucket_len),
user_key_len_(user_key_len),
target_(target) {}
bool operator()(const uint32_t first, const uint32_t second) const {
const char* first_bucket =
(first == kInvalidIndex) ? target_.data() :
&file_data_.data()[first * bucket_len_];
const char* second_bucket =
(second == kInvalidIndex) ? target_.data() :
&file_data_.data()[second * bucket_len_];
return ucomp_->Compare(Slice(first_bucket, user_key_len_),
Slice(second_bucket, user_key_len_)) < 0;
}
private:
const Slice file_data_;
const Comparator* ucomp_;
const uint32_t bucket_len_;
const uint32_t user_key_len_;
const Slice target_;
};
const BucketComparator bucket_comparator_;
void PrepareKVAtCurrIdx();
CuckooTableReader* reader_;
bool initialized_;
Status status_;
// Contains a map of keys to bucket_id sorted in key order.
std::vector<uint32_t> sorted_bucket_ids_;
// We assume that the number of items can be stored in uint32 (4 Billion).
uint32_t curr_key_idx_;
Slice curr_value_;
IterKey curr_key_;
// No copying allowed
CuckooTableIterator(const CuckooTableIterator&) = delete;
void operator=(const Iterator&) = delete;
};
CuckooTableIterator::CuckooTableIterator(CuckooTableReader* reader)
: bucket_comparator_(reader->file_data_, reader->ucomp_,
reader->bucket_length_, reader->user_key_length_),
reader_(reader),
initialized_(false),
curr_key_idx_(kInvalidIndex) {
sorted_bucket_ids_.clear();
curr_value_.clear();
curr_key_.Clear();
}
void CuckooTableIterator::InitIfNeeded() {
if (initialized_) {
return;
}
sorted_bucket_ids_.reserve(reader_->GetTableProperties()->num_entries);
uint64_t num_buckets = reader_->table_size_ + reader_->cuckoo_block_size_ - 1;
assert(num_buckets < kInvalidIndex);
const char* bucket = reader_->file_data_.data();
for (uint32_t bucket_id = 0; bucket_id < num_buckets; ++bucket_id) {
if (Slice(bucket, reader_->key_length_) != Slice(reader_->unused_key_)) {
sorted_bucket_ids_.push_back(bucket_id);
}
bucket += reader_->bucket_length_;
}
assert(sorted_bucket_ids_.size() ==
reader_->GetTableProperties()->num_entries);
std::sort(sorted_bucket_ids_.begin(), sorted_bucket_ids_.end(),
bucket_comparator_);
curr_key_idx_ = kInvalidIndex;
initialized_ = true;
}
void CuckooTableIterator::SeekToFirst() {
InitIfNeeded();
curr_key_idx_ = 0;
PrepareKVAtCurrIdx();
}
void CuckooTableIterator::SeekToLast() {
InitIfNeeded();
curr_key_idx_ = static_cast<uint32_t>(sorted_bucket_ids_.size()) - 1;
PrepareKVAtCurrIdx();
}
void CuckooTableIterator::Seek(const Slice& target) {
InitIfNeeded();
const BucketComparator seek_comparator(
reader_->file_data_, reader_->ucomp_,
reader_->bucket_length_, reader_->user_key_length_,
ExtractUserKey(target));
auto seek_it = std::lower_bound(sorted_bucket_ids_.begin(),
sorted_bucket_ids_.end(),
kInvalidIndex,
seek_comparator);
curr_key_idx_ =
static_cast<uint32_t>(std::distance(sorted_bucket_ids_.begin(), seek_it));
PrepareKVAtCurrIdx();
}
bool CuckooTableIterator::Valid() const {
return curr_key_idx_ < sorted_bucket_ids_.size();
}
void CuckooTableIterator::PrepareKVAtCurrIdx() {
if (!Valid()) {
curr_value_.clear();
curr_key_.Clear();
return;
}
uint32_t id = sorted_bucket_ids_[curr_key_idx_];
const char* offset = reader_->file_data_.data() +
id * reader_->bucket_length_;
if (reader_->is_last_level_) {
// Always return internal key.
curr_key_.SetInternalKey(Slice(offset, reader_->user_key_length_),
0, kTypeValue);
} else {
curr_key_.SetKey(Slice(offset, reader_->key_length_));
}
curr_value_ = Slice(offset + reader_->key_length_, reader_->value_length_);
}
void CuckooTableIterator::Next() {
if (!Valid()) {
curr_value_.clear();
curr_key_.Clear();
return;
}
++curr_key_idx_;
PrepareKVAtCurrIdx();
}
void CuckooTableIterator::Prev() {
if (curr_key_idx_ == 0) {
curr_key_idx_ = static_cast<uint32_t>(sorted_bucket_ids_.size());
}
if (!Valid()) {
curr_value_.clear();
curr_key_.Clear();
return;
}
--curr_key_idx_;
PrepareKVAtCurrIdx();
}
Slice CuckooTableIterator::key() const {
assert(Valid());
return curr_key_.GetKey();
}
Slice CuckooTableIterator::value() const {
assert(Valid());
return curr_value_;
}
extern InternalIterator* NewErrorInternalIterator(const Status& status,
Arena* arena);
InternalIterator* CuckooTableReader::NewIterator(
const ReadOptions& read_options, Arena* arena) {
if (!status().ok()) {
return NewErrorInternalIterator(
Status::Corruption("CuckooTableReader status is not okay."), arena);
}
if (read_options.total_order_seek) {
return NewErrorInternalIterator(
Status::InvalidArgument("total_order_seek is not supported."), arena);
}
CuckooTableIterator* iter;
if (arena == nullptr) {
iter = new CuckooTableIterator(this);
} else {
auto iter_mem = arena->AllocateAligned(sizeof(CuckooTableIterator));
iter = new (iter_mem) CuckooTableIterator(this);
}
return iter;
}
size_t CuckooTableReader::ApproximateMemoryUsage() const { return 0; }
} // namespace rocksdb
#endif